Kill pathogens without destroying food

Again and again the media is rocked by scandals over contaminated food. Thousands of people in developed countries fall ill after eating contaminated, spoiled or adulterated foods. The number of products withdrawn from sale is constantly growing.

The list of threats to food safety, as well as to the people who consume them, is much longer than well-known pathogens such as salmonella, noroviruses, or those with particularly infamous reputations.

Despite industry vigilance and the use of a range of food preservation technologies, such as heat treatment and irradiation, people continue to get sick and die from contaminated and unhealthy foods.

The challenge is to find scalable methods that will kill dangerous microbes while maintaining taste and nutritional value. This is not easy, as many methods of killing microorganisms tend to degrade these numbers, destroy vitamins, or change the structure of food. In other words, boiling lettuce can keep it, but the culinary effect will be poor.

Cold plasma and high pressure

Among the many ways to sterilize food, from microwaves to pulsed ultraviolet radiation and ozone, two new technologies are of great interest: cold plasma and high pressure processing. Neither will solve all problems, but both can help improve the security of the food supply. In one study conducted in Germany in 2010, nutrition scientists were able to eliminate more than 20% of certain strains that cause food poisoning within 99,99 seconds after applying cold plasma.

cold plasma it is a highly reactive substance composed of photons, free electrons and charged atoms and molecules that can deactivate microorganisms. Reactions in plasma also generate energy in the form of ultraviolet light, damaging microbial DNA.

Use of cold plasma

High pressure processing (HPP) is a mechanical process that puts tremendous pressure on food. However, it retains its flavor and nutritional value, which is why scientists see it as an effective way to fight microorganisms in low-moisture foods, meats, and even some vegetables. HPS is actually an old idea. Bert Holmes Hite, an agricultural researcher, first reported its use as early as 1899 while looking for ways to reduce spoilage in cow's milk. However, in his time, the installations required for hydroelectric power plants were very complex and expensive to build.

Scientists don't fully understand how HPP inactivates bacteria and viruses while leaving food untouched. They know this method attacks weaker chemical bonds that can be critical to the functioning of bacterial enzymes and other proteins. At the same time, HPP has a limited effect on covalent bonds, so the chemicals that affect the color, taste, and nutritional value of food remain virtually untouched. And since the walls of plant cells are stronger than the membranes of microbial cells, they seem to be better able to withstand high pressure.

Destruction of microbial cells by pressing methods

In recent years, the so-called "barrier" method Lothar Leistner, who combines many sanitation techniques to kill as many pathogens as possible.

plus waste management

According to scientists, the easiest way to ensure food safety is to make sure it is clean, of good quality and of known origin. Large retail chains such as Walmart in the US and Carrefour in Europe have been using blockchain technology () in combination with sensors and scanned codes to control the delivery process, origin and quality of food for some time. These methods can also help in the fight to reduce food waste. According to a Boston Consulting Group (BCG) report, around 1,6 billion tons of food is wasted worldwide every year, and if nothing is done about it, this figure could rise to 2030 billion by 2,1. Waste is present throughout value chains: from plant production to processing and storage, processing and packaging, distribution and retail, and finally re-emerging on a large scale at the end-use stage. The fight for food safety naturally leads to waste reduction. After all, food that is not damaged by microbes and pathogens is thrown out to a lesser extent.

The scale of food waste in the world

Old and new ways to fight for safe food

• Heat treatment - this group includes widely used methods, for example, pasteurization, i.e. destruction of harmful microbes and proteins. Their disadvantage is that they reduce the taste and nutritional value of products, and also that high temperature does not destroy all pathogens.
• Irradiation is a technique used in the food industry to expose food to electron, x-ray or gamma rays that destroy DNA, RNA or other chemical structures harmful to organisms. The problem is that the pollution cannot be removed. There are also many concerns about the doses of radiation that food workers and consumers must consume.
• The use of high pressures - this method blocks the production of harmful proteins or destroys the cellular structures of microbes. It is well suited for products with low water content and does not damage the products themselves. The disadvantages are high installation costs and possible destruction of more delicate food tissues. This method also does not kill some bacterial spores.
• Cold plasma is a technology under development, the principle of which has not yet been fully explained. It is assumed that active oxygen radicals are formed in these processes, which destroy microbial cells.
• UV radiation is a method used in industry that destroys the DNA and RNA structures of harmful organisms. Pulsed ultraviolet light has been found to be better suited for microbial inactivation. The disadvantages are: heating of the surface of products during prolonged exposure, as well as concerns for the health of workers in industrial enterprises where UV rays are used.
• Ozonation, an allotropic form of oxygen in liquid or gaseous form, is an effective bactericidal agent that destroys cell membranes and other structures of organisms. Unfortunately, oxidation can degrade food quality. In addition, it is not easy to control the uniformity of the entire process.
• Oxidation with chemicals (eg, hydrogen peroxide, peracetic acid, chlorine-based compounds) - used in industry in food packaging, destroys cell membranes and other structures of organisms. The advantages are simplicity and relatively low cost of installation. Like any oxidation, these processes also affect food quality. In addition, chlorine-based substances can be carcinogenic.
• Use of radio waves and microwaves - the effect of radio waves on food is the subject of preliminary experiments, although microwaves (higher power) are already used in microwave ovens. These methods are in some way a combination of heat treatment and irradiation. If successful, radio waves and microwaves could provide alternatives to many other food containment and sanitation methods.